Newton's Cradle is named after Sir Isaac Newton. It is unknown who in particular invented it but it was created in the 1960's. A Newton’s cradle is a device that demonstrates conservation of energy and momentum. It is generally made with five balls but sometimes they are made with three. When you drop one ball, the momentum and energy of its fall is transferred through the other balls to the ball on the end which comes off as a result. This ball reaches a height nearly equal to the height of the first ball that was initially dropped, but loses some energy to air resistance and the collision. Similarly when you drop two balls, two come off the other end. This is a simple action reaction phenomenon, demonstrating that each action has an equal reaction. However weird things happen when you drop a ball that is not the same mass as the others. Im going to test what happens when the ball that is being dropped is different massess than the other balls.
Procedure
I modified an existing Newton’s cradle by moving out one of the balls and replacing it with one of my own. I connected this ball to string and the string to the Newton’s cradle. I used electrical tape for both connections. I then made sure that the ball lined up well with the others. An Image of my setup is below.
I set up a video camera to record the motion of the balls of the Newton’s cradle. I made sure that a ruler was in the frame for reference. I started recording the video and then pulled the modified ball 4.4 cm horizontally away from the others and dropped it. I choose this distance because it was the distance to the edge of the base of the cradle, which was easy to reference. I recorded the motion of the Newton’s cradle and analyzed the video by using logger pro’s video analysis feature. I found how far in the x direction each ball traveled. I performed three trials of video capture. I changed the weight of the modified ball and recorded three trials for each different mass. The mass of the other four balls remained constant at 21 grams, as did the height from which I dropped them. After collecting the data I used the distance traveled in the x direction along with some mathematical relationships to calculate the rise of the ball. I then used this to calculate the amount of energy that was transferred to each ball. I then divided this amount of energy by the total starting energy to obtain the percentage of energy that was transferred to the ball. I then averaged the values for all three trials.
Results
What I measured in this experiment was the percentage of energy that was transferred to each ball. The diagram below shows which ball relates to each letter. The ball that was initially dropped has no letter.
21 gram ball
Ball
Average % of energy transferred
A
69.37
B
2.93
C
0
D
0
Total:
72.3
45 gram ball
Ball
Average % of energy transferred
A
45.42
B
1.96
C
1.44
D
0
Total:
48.82
66 gram ball
Ball
Average % of energy transferred
A
41.09
B
4.49
C
1.8
D
1.34
Total:
48.72
111 gram ball
Ball
Average % of energy transferred
A
33.17
B
9.5
C
3.48
D
2.29
Total:
48.44
Conclusions
My Results show that ball A always receives the largest percentage of energy. However as you increase the mass of the ball that you are dropping the percentage of energy transferred to A decreases and the percentage of energy transferred to the other balls (B,C, and D) increases.
One weird thing about my results is that they show a lot of energy being lost, especially on the trials where I attached the balls myself. On the balls that I attached myself roughly 50% of the energy was consistently lost. There are several sources of error that can explain this. When I attached the balls I tired to make sure that they lined up well with the other balls, any error in my placement of the ball would cause energy to be lost. Other sources of error are the video camera and logger pro. The video camera does not have a very fast frame rate and it is likely that it was missing the highest point of each balls travel in the x direction. This would result in an artificially low recording of the percentage of energy transferred to that ball. The accuracy of logger pros video analysis feature is also limited. In logger pro I had to manually set the scale, if the line I drew was not exactly the same distance as an object of known length than flawed measurement would occur. I also had to manually place points on logger pro to track each balls motion, misplacing a point would cause error. The combination of these sources of error is likely what caused such a high percentage of energy to be lost. The percentage of energy lost for the 21 gram ball is lower because this ball was already attached, and the error associated with me attaching the ball is not present.
This experiment could be improved by addressing all of the sources of error that I mentioned above. This would make the experiment more precise, and the results more accurate. More trials would also improve the experiment and increase accuracy. Another question that came up while I did this experiment is, what would happen if you dropped balls of different masses and clamped ball B in place, allowing only ball A to move. I think it would be interesting to test this experiment.
Table of Contents
Newton's Cradle
WalkerIntroduction
Newton's Cradle is named after Sir Isaac Newton. It is unknown who in particular invented it but it was created in the 1960's. A Newton’s cradle is a device that demonstrates conservation of energy and momentum. It is generally made with five balls but sometimes they are made with three. When you drop one ball, the momentum and energy of its fall is transferred through the other balls to the ball on the end which comes off as a result. This ball reaches a height nearly equal to the height of the first ball that was initially dropped, but loses some energy to air resistance and the collision. Similarly when you drop two balls, two come off the other end. This is a simple action reaction phenomenon, demonstrating that each action has an equal reaction. However weird things happen when you drop a ball that is not the same mass as the others. Im going to test what happens when the ball that is being dropped is different massess than the other balls.
Procedure
I modified an existing Newton’s cradle by moving out one of the balls and replacing it with one of my own. I connected this ball to string and the string to the Newton’s cradle. I used electrical tape for both connections. I then made sure that the ball lined up well with the others. An Image of my setup is below.
I set up a video camera to record the motion of the balls of the Newton’s cradle. I made sure that a ruler was in the frame for reference. I started recording the video and then pulled the modified ball 4.4 cm horizontally away from the others and dropped it. I choose this distance because it was the distance to the edge of the base of the cradle, which was easy to reference. I recorded the motion of the Newton’s cradle and analyzed the video by using logger pro’s video analysis feature. I found how far in the x direction each ball traveled. I performed three trials of video capture. I changed the weight of the modified ball and recorded three trials for each different mass. The mass of the other four balls remained constant at 21 grams, as did the height from which I dropped them. After collecting the data I used the distance traveled in the x direction along with some mathematical relationships to calculate the rise of the ball. I then used this to calculate the amount of energy that was transferred to each ball. I then divided this amount of energy by the total starting energy to obtain the percentage of energy that was transferred to the ball. I then averaged the values for all three trials.
Results
What I measured in this experiment was the percentage of energy that was transferred to each ball. The diagram below shows which ball relates to each letter. The ball that was initially dropped has no letter.
Conclusions
My Results show that ball A always receives the largest percentage of energy. However as you increase the mass of the ball that you are dropping the percentage of energy transferred to A decreases and the percentage of energy transferred to the other balls (B,C, and D) increases.
One weird thing about my results is that they show a lot of energy being lost, especially on the trials where I attached the balls myself. On the balls that I attached myself roughly 50% of the energy was consistently lost. There are several sources of error that can explain this. When I attached the balls I tired to make sure that they lined up well with the other balls, any error in my placement of the ball would cause energy to be lost. Other sources of error are the video camera and logger pro. The video camera does not have a very fast frame rate and it is likely that it was missing the highest point of each balls travel in the x direction. This would result in an artificially low recording of the percentage of energy transferred to that ball. The accuracy of logger pros video analysis feature is also limited. In logger pro I had to manually set the scale, if the line I drew was not exactly the same distance as an object of known length than flawed measurement would occur. I also had to manually place points on logger pro to track each balls motion, misplacing a point would cause error. The combination of these sources of error is likely what caused such a high percentage of energy to be lost. The percentage of energy lost for the 21 gram ball is lower because this ball was already attached, and the error associated with me attaching the ball is not present.
This experiment could be improved by addressing all of the sources of error that I mentioned above. This would make the experiment more precise, and the results more accurate. More trials would also improve the experiment and increase accuracy. Another question that came up while I did this experiment is, what would happen if you dropped balls of different masses and clamped ball B in place, allowing only ball A to move. I think it would be interesting to test this experiment.
References
Wikipedia-Newton's CradleNY Times-Number Play Newton's Cradle